This project aims to specify the role played by those genetic, environmental, and psychosocial factors causing blood pressure to rise in a migrant population. The Tokelauans are a Polynesian people migrating from their traditional atolls to New Zealand where by analog with other migrating Polynesians, a rise in blood pressure is expected to follow migration. Approximately one half of the population has remained in its traditional setting while the other half has migrated to New Zealand. The extensive data already collected on this population includes detailed genealogical records; a wide range of medical, sociological and physiological variables for the pre-migrant period and which is updated every 2-3 years in both the migrant and non-migrant populations; anthropometric and genetic marker data for a sub-sample of the population. By use of regression models based on the distribution of genetic relationships between individuals in similar and different environments we will attempt to estimate the influence of the genetic component and the genotype-environment interaction component on the distribution of blood pressures and related physiological variables. Particular attention will be directed to the factors influencing blood pressure in the migrant children and towards the construction of a pre-clinical "at-risk" profile for this population.